When a television, computer or other display device receives an input signal, such as a cable feed or Digital Versatile Disc (DVD) stream, this input is processed by a processing device, such as a television set-top box or other suitable device. Included within the input signal is active video information and non-active video information, such as closed captioning or extended data service information. The input signal is processed on a field-by-field basis and provided to a display device, such as a television. The active video information is displayed, wherein the non-active video information may be displayed or used for other internal processes within the set-top box or the display. For example, close captioning may be displayed on the television screen, if the user has enabled the feature. Irrespective of the users activation of extended features related to the non-active video information, a conventional set-top box typically provides this information to the display device in conjunction with the active video information.
Due to synchronization problems with the processing of the video information, the input signal is divided into active video information and non-active video information, then recombined once a full field has been processed. A problem arises due to the manner in which the non-active video information is processed, in light of the active video information. Should a program change event occur, such as a channel change, the display will simply receives the non-active video information from the new field, without receiving a notification of the change event. Therefore, the previous field non-active video information is not cleared, but rather the new field non-active video information is received as the next input. In a situation where a first channel has closed captioning data within the non-active video information and the channel is then changed, if the new channel does not have closed captioning data, the display will not reset the field and will continue to display the close captioning box from the previous channel. Typically, an internal 16-second timeout interval will eventually cause the display to be cleared from the screen. However, the viewer has already been presented with erroneous data.
Consequently, there is a need for a command processing system whereupon when a program change event is detected, the non-active video information is corrected to correspond to the updated status.